I don't know what a Ph.D. was doing seeing patients, but they certainly weren't wrong. You probably saw an MD (Medical Doctor) rather than a Ph.D. You did have gastroenteritis. What caused that gastroenteritis is anyone's guess. However, if you did not tell the doctor that you had been sucking on poison in recent days, they have no way of knowing that you have "nicotine poisoning." Still, you likely did not have nicotine poisoning because that condition is an acute condition in which the symptoms typically subside and the patient stabilize in ~4 hours. If you had nicotine poisoning, you would have been experiencing ataxia, tachycardia, hypertension, etc., all of which the worst medical doctor in Ethiopia would have caught.
People, when you go see a doctor, you are not just seeing that doctor so that s/he can assess your symptoms with some magical algorithm - you are seeking objectivity, experience and judgement. When you go to WebMD and start typing in symptoms, you are in no position to assess your condition properly. Get off of WebMD, go to iTunesU, and watch some biology lectures. An understanding of science should start there.